My NIW based I-140 application was
approved, and the I-485 application is pending. Is it a problem for my I-485
approval if I am unemployed
at the time of the I-485 processing?

Answer:

For
your I-485 application to be approved under NIW based I-140 petition, you
should
establish the prospective national benefit to the U.S. national interest after
obtaining the green card approval, even the Labor Certification was waived for
the NIW category.

If
you can not find job after the NIW I-140 approval, the USCIS may ask evidence
of prospective national benefit to the U.S. national interest by requiring
proof of your employment in the same field of work for which the NIW was
approved, then you may have problem to get I-485
application approval.